Injection molding machine and the molding method thereof

ABSTRACT

A specific mold status Ac is caused in advance in which the interval of an inner portion Xi in the parting plane direction of a parting gap C between a fixed mold  2   c  and a movable mold  2   m  during the injection filling is larger than the interval of an outer edge portion Xo and the interval of the outer edge portion Xo is equal to or lower than a predetermined size Ls including 0. A molding injection pressure Pi is set as an injection pressure at which a non-defective product can be molded and a molding mold clamping force Pc is set as a mold clamping force by which a non-defective product can be molded. During the production, a mold  2  is clamped by a molding mold clamping force Pc and the clamped mold  2  is filled with the injected resin R by a molding injection pressure Pi. After a predetermined cooling time Tc has passed, a molded piece G is removed.

TECHNICAL FIELD

This invention relates to an injection molding machine and a moldingmethod using this injection molding machine by which a mold clamped by apredetermined mold clamping force is filled with injected resin by apredetermined injection pressure to perform a molding operation.

BACKGROUND ART

Conventionally, a molding method of an injection molding machinedisclosed in Patent Publication 1 suggested by the applicant of thisapplication has been already known as a molding method of an injectionmolding machine by which molds consisting of a fixed mold and a movablemold clamped by a mold clamping apparatus at a predetermined moldclamping force are filled with injected resin by an injection apparatusat a predetermined injection pressure and an injection molding machinehaving a specific molding mode different from a general molding mode inparticular.

This molding method has an objective of securing, even in the case oflow-viscosity resin having a characteristic sensitively influenced by atemperature or a pressure for example, molded pieces having a highquality and homogeneity, achieving simpler molding conditions and easiersetting, providing easier quality control, and reducing the moldingcycle time, thereby improving the mass production and economy.Specifically, such a mold clamping apparatus is used that is a moldclamping apparatus providing the resin compression (natural compression)at least in accordance with the resin solidification in a mold, i.e., adirect pressure-type mold clamping apparatus to use a driving ram of amold clamping cylinder to displace a movable mold, or a toggle-type moldclamping apparatus in which a tie bar installed between a fixed platensupporting a fixed platen and a pressure-receiving platen includes amovable platen supporting a movable mold in a slidable manner and apressure-receiving platen and a movable platen have therebetween atoggle link mechanism and a driving mechanism section is used to drivethe toggle link mechanism to clamp the mold in a non-lockup status. Aninjection pressure (molding injection pressure) and a mold clampingforce (molding mold clamping force) that can provide a predetermined gap(mold gap) between a movable mold and a fixed mold during injectionfilling and a non-defective product are calculated and set in advance.During production, the molding mold clamping force is used to clamp themold clamping apparatus and the molding injection pressure is set as alimit pressure. The injection apparatus is driven to inject and fill theresin into the mold. Thereafter, the passage of a predetermined coolingtime is followed by the removal of a molded piece.

SUMMARY OF INVENTION Technical Problem

However, in the case of the molding method of the above-describedconventional injection molding machine, a disadvantage as describedbelow is left unsolved.

Specifically, according to this molding method, attention is paid on amold clamping apparatus that can provide the natural compression to thevolume reduction due to resin solidification in a mold. As a moldclamping apparatus for realizing this, a direct pressure-type hydraulicmold clamping apparatus providing the resin natural compression or atoggle-type mold clamping apparatus providing the mold clamping in anon-lockup status is used. In order to fill resin, a mold gap(predetermined gap) is once caused in the mold and this mold gap isgradually reduced by the natural compression due to the resinsolidification. Thus, in the case of this molding method, an interval ofthe mold gaps is important. Thus, a desired interval is set in the rangefrom 0.03 to 0.30 [mm]. This can consequently provide a desired naturalcompression or mold gap when this molding method is carried out.

By the way, according to this molding method, since attention is paid onthe interval of the mold gaps, the selection (setting) of the intervalcan achieve the original objective of providing secure molded pieceshaving a high quality and homogeneity and providing simpler moldingconditions and an easy setting, easy quality control, and a shortermolding cycle time. However, the invention does not refer to the shapeof the mold gap. This method uses the structure characteristic of themold clamping apparatus as a means of obtaining the mold gap. However,the invention does not refer to factors other than this.

As described above, the molding method of the injection molding machinein the above-described conventional case does not consider the shape ofthe mold gap and does not consider factors other than the structurecharacteristic of the mold clamping apparatus as a means of obtainingthe mold gap. Thus, there has been a need to further improve andoptimize the molding method.

It is an objective of this invention to provide an injection moldingmachine and the molding method thereof by which the disadvantageexisting in the above-described prior art is solved.

Solution to Problem

In order to solve the above-described disadvantage, an injection moldingmachine M according to this invention is configured to include a themold clamping apparatus Mc to clamp a mold 2 consisting of a fixed mold2 c and a movable mold 2 m by a predetermined mold clamping force and anthe injection apparatus Mi to inject resin R to the mold-clamped mold 2by a predetermined injection pressure. The injection molding machineincludes the mold clamping apparatus Mc to allow, in accordance with thesolidification of resin R in a mold 2, at least the natural compressionof the resin R by the elastic recovery of the mold 2. During theinjection filling, a specific mold status Ac is caused in which theinterval of an inner portion Xi in the parting plane direction of aparting gap C between the fixed mold 2 c and the movable mold 2 m islarger than the interval of the outer edge portion Xo and the intervalof the outer edge portion Xo is equal to or smaller than a predeterminedsize Ls including 0. The injection molding machine is characterized inincluding a control means 3 including a setting function Fs for settinga molding injection pressure Pi that is an injection pressure at which anon-defective product can be molded and a molding mold clamping force Pcthat is a mold clamping force by which a non-defective product can bemolded and a control function Fc for using, during the production, themolding mold clamping force Pc to clamp the mold 2 and for injecting andfilling the resin R into the clamped mold 2 by the molding injectionpressure Pi and for performing, after the passage of the predeterminedcooling time Tc, a control for removing the molded piece G.

On the other hand, according to the molding method of the injectionmolding machine according to this invention, in order to solve theabove-described disadvantage, the mold 2 consisting of the fixed mold 2c and the movable mold 2 m clamped by the mold clamping apparatus Mc atthe predetermined mold clamping force are filled with the injected resinR by the injection apparatus Mi at the predetermined injection pressureto perform a molding operation. During the molding operation, the moldclamping apparatus Mc is used that allows, in accordance with thesolidification of the resin R in the mold 2, at least the naturalcompression of the resin R due to the elastic recovery of the mold 2.The specific mold status Ac is caused in advance during the injectionfilling in which the interval of the inner portion Xi in the partingplane direction of the parting gap C between the fixed mold 2 c and themovable mold 2 m is larger than the interval of the outer edge portionXo and the interval of the outer edge portion Xo is equal to or smallerthan the predetermined size Ls including 0. The injection moldingmachine is characterized in that the molding injection pressure Pi thatis an injection pressure at which a non-defective product can be moldedand the molding mold clamping force Pc that is a mold clamping force bywhich a non-defective product can be molded are set and, during theproduction, the molding mold clamping force Pc is used to clamp the mold2 and the resin R is injected and filled into the clamped mold 2 by themolding injection pressure Pi and, after the passage of thepredetermined cooling time Tc, the molded piece G is removed.

Advantageous Effects of Invention

The injection molding machine M and the molding method thereof accordingto this invention provide remarkable effects as described below.

(1) During the injection filling, the specific mold status Ac is causedin which the interval of the inner portion Xi in the parting planedirection of the parting gap C between the fixed mold 2 c and themovable mold 2 m is larger than the interval of the outer edge portionXo and the interval of the outer edge portion Xo is equal to or lowerthan the predetermined size Ls including 0. This consequently allows theouter edge portion Xo side at the parting gap C to be different from theinterval (size) at the inner portion Xi side. Specifically, at the innerportion Xi side, the interval of the parting gap C providing the optimalnatural compression to the resin R can be set. At the outer edge portionXo side, from the viewpoint of the degassing or burr prevention forexample of a mold cavity, the optimal interval of the parting gap C canbe set for example, thereby providing the optimization of the intervaland shape of the parting gap C. This can consequently secure the effectof the conventional molding method for setting the interval of theparting gap C only, i.e., molded pieces G having a high quality andhomogeneity and also can provide effects including the ones to achievesimpler molding conditions and easier setting, to provide easier qualitycontrol, and to reduce the molding cycle time for example.

(2) According to a preferred embodiment, the control means 3 isconfigured to include, during the injection filling, a gap statusdetector 11 that detects the fixed mold 2 c abutted to the outer edgeportion Xo and the relative change angle Qm between the outer faces 2 cfand 2 mf in the movable mold 2 m or a physical amount corresponding tothis change angle Qm (the measurement distance Lc). The control means 3also includes a molding machine controller 12 that performs a control tomaintain the specific mold status Ac based on the change angle Qmobtained from the gap status detector 11 or the physical amountcorresponding to this change angle Qm (the measurement distance Lc).This configuration can directly detect the shape change of the partinggap C between the fixed mold 2 c and the movable mold 2 m, i.e., thedeflection of the mold 2 due to the elastic deformation in an easy andaccurate manner.

(3) According to a preferred embodiment, a gap status detector 11 uses anon-contact-type distance measurement sensor 13 that is provided betweenthe outer face 2 cf of the fixed mold 2 c and the outer face 2 mf of themovable mold 2 m and that consists of a projection section 13 p providedat one of the fixed mold 2 c and the movable mold 2 m and a reflectingsection 13 r provided at the other. This distance measurement sensor 13is used to detect a measurement distance Lc showing a physical amountcorresponding to the change angle Qm. By this configuration, themeasurement distance Lc obtained from the distance measurement sensor 13can be used to easily detect the change angle Qm between the outer faces2 mf and 2 cf of the mold 2, thus providing easy maintenance andadjustment (correction) and realizing a relatively-low cost.

(4) According to a preferred embodiment, the projection section 13 p andthe reflecting section 13 r provided in the distance measurement sensor13 are provided at a position away from the outer faces 2 mf and 2 cf inthe outer direction in the orthogonal direction by a fixed distance Lxor more. This configuration can detect the change angle Qm or thephysical amount corresponding to this change angle Qm (the measurementdistance Lc) in a mechanically-amplified manner, thus allowing even aminute angle change to be securely and accurately detected.

(5) According to a preferred embodiment, the projection section 13 p andthe reflecting section 13 r are supported by support stays 14 p and 14 rhaving a predetermined length protruding from outer faces 2 cf and 2 mf,respectively. This configuration can more easily realize, by arelatively-simple structure, conditions under which the projectionsection 13 p and the reflecting section 13 r are away from the outerfaces 2 mf and 2 cf in the outer direction in the orthogonal directionby a fixed distance Lx or more.

(6) According to a preferred embodiment, the projection section 13 p andthe reflecting section 13 r have support mechanisms 15 p and 15 r,respectively. The support stays 14 p and 14 r are used to support thesupport mechanisms 15 p and 15 r. The support mechanisms 15 p and 15 rare used to adjust at least the distance Lx from the outer faces 2 cfand 2 mf to the projection section 13 p and the reflecting section 13 r.This configuration can optionally perform the sensitivity adjustment(position adjustment) of the distance measurement sensor 13 and also caneasily add another adjustment mechanism such as an angle adjustmentmechanism to the projection section 13 p and the reflecting section 13r.

(7) According to a preferred embodiment, the projection section 13 p andthe reflecting section 13 r included in the distance measurement sensor13 are arranged so as to have a predetermined interval Lo during themold clamping prior to the injection filling so that at least a changedistance Ln in the shortening direction can be detected. Thisconfiguration can set the detection result of the distance measurementsensor 13 at the predetermined interval Lo to 0 (zero reset position),thereby easily detecting the specific mold status Ac based on the changedistance Ln in the shortening direction.

(8) According to a preferred embodiment, the setting function Fc of thecontrol means 3 is allowed to have a function to set the moldinginjection pressure Pi as a limit pressure Ps during the production. Thisconfiguration can always maintain the molding injection pressure Piwithout requiring a control to a pressure.

(9) According to a preferred embodiment, the interval of the outer edgeportion Xo at the parting gap C is set to 0.3 [mm] or less. Thisconfiguration can add the interval-like factor of the parting gap C inthe conventional case to the shape of the parting gap C, thusdiversifying the parting gap C to thereby increase the setting freedomfor optimization.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1: An extraction diagram illustrating a waveform display sectiondisplayed on a display screen of a molding machine controller in aninjection molding machine according to a preferred embodiment of thisinvention.

FIG. 2: A illustrates the principle of the molding method using theinjection molding machine.

FIG. 3: A illustrates the configuration of a bottom face of a distancemeasurement sensor provided in the injection molding machine.

FIG. 4: A illustrates the configuration of a side face of the distancemeasurement sensor provided in the injection molding machine.

FIG. 5: A bottom cross-sectional view illustrating resin filled in amold provided in the injection molding machine is fixated due to thenatural compression.

FIG. 6: A bottom cross-sectional view illustrating resin filled in themold provided in the injection molding machine and the mold has noelastic deformation.

FIG. 7: A bottom cross-sectional view illustrating resin filled in themold provided in the injection molding machine and the mold has elasticdeformation.

FIG. 8: A bottom cross-sectional view illustrating resin filled in themold provided in the injection molding machine and the mold has elasticdeformation and is opened.

FIG. 9: A illustrates the configuration of the injection molding machinethat can carry out the molding method.

FIG. 10: A block system diagram of a control means that can carry outthe molding method.

FIG. 11: A flowchart for explaining a processing procedure for settingthe molding conditions in the injection molding machine.

FIG. 12: A flowchart for explaining a pre-filling step in the productionusing the molding method.

FIG. 13: A flowchart for explaining the processing procedure of afilling molding step in the production using the molding method.

DESCRIPTION OF EMBODIMENTS

Next, the following section will describe a preferred embodiment of thisinvention based on the drawings. The attached drawings do not intend tolimit this invention but is made to promote the understanding of thisinvention. Regarding well-known matters, the detailed descriptionthereof will not be provided in order to not to obscure the invention.

First, the following section will describe the entire main configurationof the injection molding machine M according to this embodiment withreference to FIG. 9.

In FIG. 9, the reference numeral M denotes an injection molding machineincluding an injection apparatus Mi and a mold clamping apparatus Mc.The injection apparatus Mi has a heating tube 21 in which the front endhas an injection nozzle 21 n and the rear part has a hopper 21 h,respectively. The heating tube 21 is inserted with a screw 22 and therear end of the heating tube 21 has a screw driving section 23. Thescrew driving section 23 has an injection cylinder (hydraulic cylinder)24 including therein a single rod-type injection ram 24 r. A ram rod 24rs protruding to the front side of the injection cylinder 24 isconnected to the rear end of the screw 22. The rear end of the injectionram 24 r is spline-connected to the shaft of the measurement motor (oilmotor) 25 attached to the injection cylinder 24. The reference numeral26 denotes an injection apparatus moving cylinder to move the injectionapparatus Mi in the forward or rearward direction so that the nozzletouches the mold 2 or to cancel the touch. This configuration allows theinjection nozzle 21 n of the injection apparatus Mi to touch the mold 2,thereby allowing the cavity of the mold 2 to be filled with injectedmolten (plasticized) resin R (FIG. 5).

On the other hand, the mold clamping apparatus Mc is a directpressure-type hydraulic mold clamping apparatus to use the driving ram27 r of the mold clamping cylinder (hydraulic cylinder) 27 to displacethe movable mold 2 m. This mold clamping apparatus Mc has a fixed platen28 having a fixed position and being provided away therefrom and amovable platen 30 slidably installed to a plurality of tie bars 29 . . .installed among mold clamping cylinders 27. This movable platen 30 isfixed with the tip end of the ram rod 27 rs forwardly protruding fromthe mold clamping cylinder 27. The fixed platen 28 is attached with thefixed mold 2 c. The movable platen 30 is attached with the movable mold2 m. The fixed mold 2 c and the movable mold 2 m constitute the mold 2.This can consequently allow the mold clamping cylinder 27 to open orclose and to clamp the mold 2.

On the other hand, the reference numeral 35 denotes a hydraulic circuitthat includes a variable delivery hydraulic pump 36 functioning as ahydraulic driving source and a valve circuit 37. The 36 includes a pumpsection 38 and a servo motor 39 for driving this pump section 38 torotate. The reference numeral 40 denotes a rotary encoder to detect therotation number of the servo motor 39. The pump section 38 includestherein a pump body 41 constituted by a tilted plate-type piston pump.Thus, when the pump section 38 includes a tilted plate 42 and the tiltedplate 42 has an increased inclination angle (tilted plate angle), thepump body 41 has a pump piston having an increased stroke and thedischarge flow rate is increased and the tilted plate angle is reduced,thereby allowing the pump piston to have a reduced stroke and a reduceddischarge flow rate. Thus, by setting the tilted plate angle to apredetermined angle, such a fixed discharge flow rate can be set forwhich a discharge flow rate (maximum capacity) is fixed to apredetermined level. The tilted plate 42 has a control cylinder 43 and areturn spring 44. The control cylinder 43 is connected to the dischargeopening of the pump section 38 (the pump body 41) via a switching valve(electromagnetic valve) 45. This can consequently control the controlcylinder 43 to thereby change the angle of the tilted plate 42 (tiltedplate angle).

The pump section 38 has an inlet connected to an oil tank 46. The pumpsection 38 has a discharge opening connected to the primary side of thevalve circuit 37. The secondary side of the valve circuit 37 isconnected to the injection cylinder 24, a measurement motor 25, a moldclamping cylinder 27, an ejector cylinder 31 (FIG. 9), and an injectionapparatus moving cylinder 26 in the injection molding machine M. Thus,the valve circuit 37 has switching valves (electromagnetic valves)connected to the injection cylinder 24, the measurement motor 25, themold clamping cylinder 27, the ejector cylinder 31, and the injectionapparatus moving cylinder 26, respectively. The respective switchingvalves are configured by required attached hydraulic components forexample such as one or more or two or more valve components and have atleast a switching function related to the supply, stoppage, anddischarge of hydraulic oil to the injection cylinder 24, the measurementmotor 25, the mold clamping cylinder 27, the ejector cylinder 31, andthe injection apparatus moving cylinder 26.

As a result, by controlling the rotation number of the servo motor 39 ina variable manner, the discharge flow rate and the discharge pressure ofthe variable delivery hydraulic pump 36 are allowed to be variable.Based on this, the injection cylinder 24, the measurement motor 25, themold clamping cylinder 27, the ejector cylinder 31, and the injectionapparatus moving cylinder 26 described above can be subjected to adriving control and the respective operation steps can be controlled inthe molding cycle. As described above, the use of the variable deliveryhydraulic pump 36 for which a change of the tilted plate angle can beused to set a fixed discharge flow rate can set the pump capacity to apredetermined fixed discharge flow rate (maximum capacity) and canprovide a variable discharge flow rate and a discharge pressure based onthe fixed discharge flow rate. Thus, the control by a control system canbe carried out easily and smoothly.

Next, the following section will describe the configuration of thecontrol means 3 in the injection molding machine M according to thisembodiment with reference to FIG. 3 to FIG. 10.

The control means 3 performs a processing to realize the molding methodof the injection molding machine M according to this embodiment. Thebasic functions include the one to cause the specific mold status Acduring the injection filling in which the interval of the inner portionXi in the parting plane direction of the parting gap C between the fixedmold 2 c and the movable mold 2 m is larger than the interval of theouter edge portion Xo and the interval of the outer edge portion Xo isequal to or smaller than the predetermined size Ls including 0, thesetting function Fs for setting the molding injection pressure Pi thatis an injection pressure at which a non-defective product can be moldedand the molding mold clamping force Pc that is a mold clamping force bywhich a non-defective product can be molded, and the control function Fcfor using, during the production, the molding mold clamping force Pc toclamp the mold 2 and for injecting and filling the resin R into theclamped mold 2 by the molding injection pressure Pi and for removing themolded piece G after the passage of the predetermined cooling time Tc.

In order to realize this, the control means 3 has the gap statusdetector 11 and the molding machine controller 12 shown in FIG. 9 andFIG. 10. The gap status detector 11 uses a distance measurement sensor13 shown in FIG. 3 and FIG. 4, i.e., the distance measurement sensor 13provided between the outer face 2 cf of the fixed mold 2 c abutted tothe outer edge portion Xo of the parting gap C and the outer face 2 mfof the movable mold 2 m. The illustrated distance measurement sensor 13is a non-contact distance measurement sensor including the projectionsection 13 p provided on the outer face 2 cf of the fixed mold 2 c andthe reflecting section 13 r provided on the outer face 2 mf of themovable mold 2 m. This can allow ultrasonic waves or laser light(hereinafter referred to as measurement light) to be projected from theprojection section 13 p and measurement light reflected from thereflecting section 13 r is received to thereby measure the distancebetween the projection section 13 p and the reflecting section 13 r.

As described above, in order to configure the gap status detector 11,the non-contact distance measurement sensor 13 is provided that isprovided between the outer face 2 cf of the fixed mold 2 c and the outerface 2 mf of the movable mold 2 m and that consists of the projectionsection 13 p provided at one of the fixed mold 2 c and the movable mold2 m and the reflecting section 13 r provided at the other. This distancemeasurement sensor 13 is used to detect the change angle Qm, i.e., thechange angle Qm between the outer face 2 mf of the movable mold 2 m andthe outer face 2 cf of the fixed mold 2 c in the mold 2 or themeasurement distance Lc showing a physical amount corresponding to thischange angle Qm. This can allow the measurement distance Lc obtainedfrom the distance measurement sensor 13 to easily detect the changeangle Qm between the outer faces 2 mf and 2 cf of the mold 2, thusadvantageously providing the maintenance and adjustment (correction) inan easy manner and with a relatively-low cost.

In this case, the projection section 13 p and the reflecting section 13r are respectively provided at positions away from the outer faces 2 mfand 2 cf in the outer direction in the orthogonal direction by the fixeddistance Lx or more. If conditions using a distance equal or longer thanthis distance Lx are used, an increase of the distance of the conditionsprovides advantageous measurement but causes an increased protrusionlength, which is a distracting existence. In order to avoid such adistracting existence, the distance can be basically selected to beequal to or longer than 10 [mm] and desirably can be selected in a rangefrom 10 to 100 [mm] and optimally can be selected in a range from 20 to50 [mm].

Thus, as shown in FIG. 3, the projection section 13 p has, at theneighborhood of the outer edge portion Xo, a round bar-like support stay14 p provided in a protruding manner on the outer face 2 cf of the fixedmold 2 c. This support stay 14 p is used to support the projectionsection 13 p including the support mechanism 15 p to thereby secure thedistance Lx. Similarly, the projection section 13 p also has, at theneighborhood of the outer edge portion Xo, a round bar-like support stay14 r provided in a protruding manner on the outer face 2 mf of themovable mold 2 m. This support stay 14 r is used to support thereflecting section 13 r including the support mechanism 15 r to therebysecure the distance Lx.

The support mechanism 15 p includes an adjustment handle 15 ph.Loosening this adjustment handle 15 ph can adjust the position of theprojection section 13 p on support stay 14 p (vertical position), thehorizontal position of the projection section 13 p, and the angle of theprojection section 13 p (direction). Tightening the adjustment handle 15ph can fix the posture of the projection section 13 p. Similarly, thesupport mechanism 15 r includes an adjustment handle 15 rh. Looseningthis adjustment handle 15 rh can adjust the position of the reflectingsection 13 r on the support stay 14 r (vertical position), thehorizontal position of the reflecting section 13 r, and the angle of thereflecting section 13 r (direction). Tightening the adjustment handle 15rh can fix the posture of the reflecting section 13 r.

As described above, the projection section 13 p and the reflectingsection 13 r provided in the distance measurement sensor 13 are providedat positions away from the outer faces 2 mf and 2 cf in the outerdirection of the orthogonal direction by the fixed distance Lx or more.This configuration can detect the change angle Qm or the physical amountcorresponding to this change angle Qm (the measurement distance Lc) in amechanically-amplified manner, thus advantageously detecting even aminute angle change in a secure and accurate manner. The projectionsection 13 p and the reflecting section 13 r are respectively supportedby the support stays 14 p and 14 r having a predetermined lengthprovided on the outer faces 2 cf and 2 mf in a protruding manner. Thus,conditions for providing the projection section 13 p and the reflectingsection 13 r at positions away from the outer faces 2 mf and 2 cf in theouter direction in the orthogonal direction by the fixed distance Lx ormore can be easily realized by a relatively-simple structure. Inaddition, the projection section 13 p and the reflecting section 13 rrespectively have the support mechanisms 15 p and 15 r. The supportstays 14 p and 14 r support the support mechanisms 15 p and 15 r. Thesupport mechanisms 15 p and 15 r can be used to adjust at least thedistance Lx from the outer faces 2 cf and 2 mf to the projection section13 p and the reflecting section 13 r. This configuration has anadvantage that this configuration can optionally perform the sensitivityadjustment (position adjustment) of the distance measurement sensor 13and can easily add other adjustment mechanisms such as angle adjustmentmechanism to the projection section 13 p and the reflecting section 13r.

The projection section 13 p and the reflecting section 13 r included inthe distance measurement sensor 13 are provided so as to have thepredetermined interval Lo during the mold clamping prior to theinjection filling and to be able to detect at least the change distanceLn in the shortening direction (negative direction). This configurationcan allow an interval of the inner portion Xi in parting plane directionat the parting gap C caused between the movable mold 2 m and the fixedmold 2 c to be larger than the interval of outer edge portion Xo andthus the change angle Qm is also changed. Thus, as shown in FIG. 10, thereflecting section 13 r is mainly inclined and is closer to theprojection section 13 p side. This can consequently detect thedeflection of the mold 2 (the movable mold 2 m) due to the elasticdeformation.

As described above, the projection section 13 p and the reflectingsection 13 r included in the distance measurement sensor 13 are providedso as to have the predetermined interval Lo during the mold clampingprior to the injection filling and to be able to detect at least thechange distance Ln in the shortening direction. This configuration caneasily detect, by setting the detection result of the distancemeasurement sensor 13 at the predetermined interval Lo to 0 (zero resetposition), the specific mold status Ac based on the change distance Lnin the shortening direction (negative direction). On the other hand,when the change distance Lm in the increasing direction (positivedirection) is detected, it can be detected that the movable mold 2 m isdisplaced in the open direction without having elastic deformation.

FIG. 5 to FIG. 8 show various embodiments of the parting opening amountLm and the parting gap C. The parting gap C basically means a gap causedby the deflection of the mold 2 (the movable mold 2 m) due to theelastic deformation. The parting opening amount Lm means a gap caused bythe movable mold 2 m displaced in the open direction without causing themold 2 to have elastic deformation.

FIG. 5 illustrates a status in which the mold cavity is filled with theresin R and the resin R is fixated through cooling. This status isbasically the same as the mold clamping status in which the resin R isnot filled. Thus, the movable mold 2 m is not displaced or deflected. Inthis status, the detection result of the distance measurement sensor 13shows the distance Lo. This distance Lo is set to 0 position (zero resetposition).

FIG. 6 illustrates a status in which, without causing the movable mold 2m to have deflection due to elastic deformation, the movable mold 2 m isdisplaced in the open direction to cause a gap corresponding to theparting opening amount Lm. This is a case when the molding methoddisclosed in Patent Publication 1 is used. The detected distance isLo(0)+Lm. The resin R has natural compression mainly provided by theaction of the mechanism side in the mold clamping apparatus Mc. Asdescribed above, when the change of the measurement distance Lc in theincreasing direction (positive direction) is detected, it can bedetected that the movable mold 2 m is displaced in the open directionwithout having elastic deformation.

On the other hand, FIG. 7 shows a case where the interval of the innerportion Xi of the parting gap C in the parting plane direction is largerthan the interval of outer edge portion Xo and the change angle Qm iscaused. In this case, the mold 2 (the movable mold 2 m) has elasticdeformation and is deflected. Thus, the reflecting section 13 r ismainly inclined and is closer to the projection section 13 p side.Therefore, by setting the detection result of the distance measurementsensor 13 at the interval Lo to 0 position, then the change distance Lncan be caused in the shortening direction (negative direction), thuseasily detecting that the mold 2 is in the specific mold status Ac.

FIG. 8 shows a case where the change distance Ln (the parting gap C) inthe shortening direction and the parting opening amount Lm in theincreasing direction are both generated and thus a compound distanceLo(0)−Ln+Lm is caused. Thus, the mold 2 shown in FIG. 7 and FIG. 8 isallowed to have the specific mold status Ac used when the moldingoperation is performed by the molding method according to thisembodiment.

On the other hand, a hydraulic circuit 35 is configured so that theprimary side of the valve circuit 37 has a pressure sensor 47 fordetecting a hydraulic pressure and a temperature sensor 48 for detectingan oil temperature. The projection section 13 p, the pressure sensor 47,and the temperature sensor 48 provided in distance measurement sensor 13are connected to a sensor port in the molding machine controller 12.

The molding machine controller 12 has a display 61 attached to thismolding machine controller 12. The molding machine controller 12 has aservo amplifier 64 as shown in FIG. 10. The output section of this servoamplifier 64 is connected to the servo motor 39. The servo amplifier 64has an encoder pulse input section connected to a rotary encoder 40. Asshown in FIG. 10, the molding machine controller 12 has a control signaloutput port connected to the valve circuit 37.

The molding machine controller 12 includes a controller body 63 and theservo amplifier 64. The controller body 63 has a computer functionincluding a CPU and hardware such as an internal memory. Thus, theinternal memory has a program area 63 p for storing various programsincluding a control program (software) to execute various calculationprocessings and various control processings (sequence control) and alsohas a data area 63 m that can store various pieces of data (database)for example. In particular, the program includes a control program(sequence control program) to perform the molding operation using themolding method according to this embodiment. Thus, during the nextfunction, i.e., during the injection filling, the specific mold statusAc is caused in which the interval of the inner portion Xi in theparting plane direction of the parting gap C between the fixed mold 2 cand the movable mold 2 m is larger than the interval of the outer edgeportion Xo and the interval of the outer edge portion Xo is equal to orsmaller than the predetermined size Ls including 0. This also canperform the setting function Fs for setting the molding injectionpressure Pi that is an injection pressure at which a non-defectiveproduct can be molded and the molding mold clamping force Pc that is amold clamping force by which a non-defective product can be molded andthe control function Fc for using, during the production, the moldingmold clamping force Pc to clamp the mold 2 and for injecting and fillingthe resin R into the clamped mold 2 by the molding injection pressure Piand for removing the molded piece G after the passage of thepredetermined cooling time Tc.

On the other hand, the display 61 has a display body 61 d and a touchpanel 61 t attached to this display body 61 d. This display body 61 dand the touch panel 61 t are connected to the controller body 63 via adisplay interface 62. Thus, this touch panel 61 t can be used to performvarious setting operations and selection operations for example.

As described above, the control means 3 is configured to include the gapstatus detector 11 that detects the fixed mold 2 c abutted to the outeredge portion Xo and the relative change angle Qm between the outer faces2 cf and 2 mf in the movable mold 2 m or a physical amount correspondingto this change angle Qm (the measurement distance Lc) and the moldingmachine controller 12 that performs a control to maintain the specificmold status Ac based on the change angle Qm obtained from the gap statusdetector 11 or the physical amount corresponding to this change angle Qm(the measurement distance Lc). This configuration can directly detectthe shape change of the parting gap C between the fixed mold 2 c and themovable mold 2 m, i.e., the deflection of the mold 2 due to the elasticdeformation in an easy and accurate manner.

Next, the following section will specifically describe the operation ofthe injection molding machine M including the molding method accordingto this embodiment with reference to FIG. 1 to FIG. 13.

First, the following section will describe the outline of the moldingmethod according to the invention with reference to FIG. 2. First, atest molding is performed to calculate the molding mold clamping forcePc and the molding injection pressure Pi used for the production thatare set as molding conditions. The molding mold clamping force Pc andthe molding injection pressure Pi are calculated under the following twoconditions: the specific mold status Ac is caused in which the partinggap C is caused during the injection filling between the fixed mold 2 cand the movable mold 2 m and the interval of the inner portion Xi in theparting plane direction of the parting gap C is larger than the intervalof the outer edge portion Xo and the interval of the outer edge portionXo is equal to or lower than the predetermined size Ls including 0; andthe molded piece G is prevented from having a molding defect such asburr, sink mark, and warpage. The production is carried out under thefollowing two conditions: the set molding mold clamping force Pc is usedto perform the mold clamping; and the molding injection pressure Pi isset to the limit pressure Ps. The resin R is provided by a simpleinjection filling.

In this case, the status of the parting gap C is acquired based on thedetection result of the measurement distance Lc obtained from thedistance measurement sensor 13. Specifically, the status in which theinterval of the inner portion Xi of the parting gap C in the partingplane direction is larger than the interval of the outer edge portion Xois a status in which the mold 2 (the movable mold 2 m in particular) hasdeflection due to elastic deformation. Thus, as shown in FIG. 7 and FIG.10, the change angle Qm is caused between the outer face 2 mf of themovable mold 2 m and the outer face 2 cf of the fixed mold 2 c, thuscausing the support stay 14 p to incline by the change angle Qm. Thiscauses the reflecting section 13 r to be closer to the projectionsection 13 p side. Thus, the measurement distance Lc showing thedetection result obtained from the distance measurement sensor 13changes from 0 by an amount of Ln in the shortening direction (negativedirection).

FIG. 2 shows the typical change characteristic of the measurementdistance Lc causing the specific mold status Ac. In the case of FIG. 2,the time point “to” shows the start of the injection filling. At thetime point “to”, the measurement distance Lc is set to 0. When the mold2 is filled with the resin R, the resin pressure in the mold 2 causesthe movable mold 2 m to be slightly displaced in the open direction(i.e., the increasing direction). FIG. 2 shows this change distance bythe reference numeral Lcp. This change distance Lcp is the partingopening amount Lm shown in FIG. 6. Thus, this parting opening amount Lmis selected as the molding mold clamping force Pc and the moldinginjection pressure Pi so as to be equal to or smaller than thepredetermined size Ls including 0. The “Ls” as an interval of this outeredge portion Xo is desirably set to 0.3 [mm] or less. By the setting asdescribed above, the shape of the parting gap C can additionally havethe interval-like factor of the parting gap C in the conventional case,thus diversifying the parting gap C to thereby increase the settingfreedom for optimization.

When the mold 2 is filled with the resin R, the pressure in the mold 2increases to cause a phenomenon in which the inner portion of themovable mold 2 m is swelled, i.e., the deflection due to the elasticdeformation is caused, thereby causing the specific mold status Ac. Thedeflection of the movable mold 2 m causes the measurement distance Lcacquired from the distance measurement sensor 13 to be displaced in theshortening direction. Thus, the measurement distance Lc changes from 0to Ln as shown in FIG. 2 in the shortening direction (negativedirection). Then, when the filling operation is completed, a coolingoperation is performed. Then, the mold 2 (the movable mold 2 m)elastically recovers. This elastic recovery action provides the naturalcompression to the resin R. As a result, the magnitude of themeasurement distance Lc obtained from the distance measurement sensor 13also gradually changes to the 0 side.

As described above, during the injection filling, the mold 2 hasdeflection due to the elastic deformation to thereby cause the partinggap C. This parting gap C has the specific mold status Ac in which theinterval of the inner portion Xi in the parting plane direction of theparting gap C is larger than the interval of the outer edge portion Xoand the interval of the outer edge portion Xo is equal to or smallerthan the predetermined size Ls including 0. As a result, during thecooling, the elastic recovery of the mold 2 provides naturalcompression. Thus, even when the behavior of the mold 2 injected andfilled by the injection apparatus Mi is unstable, the mold clampingapparatus Mc adopts to the unstable behavior of the resin R, thusproviding a molded piece having the highest quality and homogeneity.

Next, the following section will describe a specific processingprocedure. First, the setting function Fs in the control means 3 is usedto calculate the molding injection pressure Pi and the molding moldclamping force Pc as molding conditions. The calculated moldinginjection pressure Pi and molding mold clamping force Pc are set asmolding conditions. FIG. 11 is a flowchart illustrating a processingprocedure to calculate and set the molding injection pressure Pi and themolding mold clamping force Pc.

By the way, in order to cause the specific mold status Ac during theinjection filling in which the interval of the inner portion Xi in theparting plane direction of the parting gap C caused between the fixedmold 2 c and the movable mold 2 m is larger than the interval of theouter edge portion Xo and the interval of the outer edge portion Xo isequal to or smaller than the predetermined size Ls including 0, then themold clamping apparatus Mc must be selected that provides, in accordancewith the solidification of the resin R in the mold 2, at least thenatural compression of resin R due to the elastic recovery of the mold2.

The provision of the specific mold status Ac as described above isclosely related to the magnitude of the mold clamping force and theselection of the magnitude of the injection pressure and the materialand structure of the mold 2. Thus, the provision of the specific moldstatus Ac may be achieved by selecting, in advance, the material andstructure of the mold 2 or by combining the material and structure ofthe mold 2 with the magnitude of the mold clamping force and themagnitude of the injection pressure. The structure of the mold 2 itselfmay be, for example, the one as shown in FIG. 5 in which the movablemold 2 m includes therein an arrangement space 2 ms to store an ejectormechanism 65 so that the inner portion of the movable mold 2 m can beeasily deflected to the outer edge portion. The reference numeral 65 p .. . denotes an ejector pin provided in the ejector mechanism 65 that isdisplaced in the forward or rear direction.

The following section will describe specific processings in a sequentialmanner. First, the injection pressure as injection conditions at theinjection apparatus Mi side is initially set by an injection pressuresetting section (not shown) in the molding machine controller 12. Theinjection pressure at this time can be set as an injection pressurebased on the capability (driving force) of the injection apparatus Mi(Step S1). In this case, the injection pressure can be calculated basedon the magnitude of the hydraulic pressure detected by the pressuresensor 47 in the hydraulic circuit 35 connected to the injectioncylinder 24. The injection pressure is a value that is not required tobe accurately calculated as an absolute value. Thus, the magnitude ofthe detected hydraulic pressure may be used or the pressure may beconverted to an injection pressure by calculation.

Next, the mold clamping force functioning as mold clamping conditions atthe mold clamping apparatus Mc side is initially set by the moldclamping force setting section (not shown) in the molding machinecontroller 12. The mold clamping force at this time can be set as a moldclamping force based on the capability (driving force) of the moldclamping apparatus Mc (Step S2). In this case, the mold clamping forcecan be calculated based on the hydraulic pressure detected by thepressure sensor (hydraulic sensor) 47 in the hydraulic circuit 35connected to the mold clamping cylinder 27. The mold clamping force hasa value that is not required to be accurately calculated as an absolutevalue. Thus, the magnitude of the detected hydraulic pressure may beused or the pressure may be converted to the mold clamping force bycalculation.

The hydraulic circuit 35 is switched by the valve circuit 37 andfunctions as a hydraulic circuit of the mold clamping apparatus Mc sideduring the mold clamping and functions as a hydraulic circuit of theinjection apparatus Mi side during the injection. By detecting theinjection pressure and the mold clamping force by the pressure sensor 47as described above, the setting related to the molding mold clampingforce Pc and the molding injection pressure Pi can be performed easily.Furthermore, it is not required to accurately set the molding moldclamping force Pc and the molding injection pressure Pi as an absolutevalue, thus providing an accurate operation control having less errorfactors.

Next, the initially-set injection pressure is subjected to anoptimization processing to thereby calculate the molding injectionpressure Pi used for the production and the initially-set mold clampingforce is subjected to an optimization processing to thereby calculatethe molding mold clamping force Pc used for the production (Steps S3 andS4). The following section will describe an example of the method ofoptimizing the mold clamping force and the injection pressure.

First, the initially-set mold clamping force and the injection pressureare used to perform a test molding. By depressing a not-shown moldingstart button, the mold clamping operation is performed and theinitially-set conditions are used to perform the test molding using themold 2. When the mold clamping force is set to have a high value, noburr is caused and sink mark, warpage, or a degassing status tend tohave a defect or a slight defect. By changing the magnitude of the moldclamping force and the magnitude of the injection pressure in a stagedmanner and by performing the test molding at the respective stages, thestatus of the parting gap C between the fixed mold 2 c and the movablemold 2 m is acquired from the distance measurement sensor 13 and isdisplayed by the waveform display section 61 v in the screen of thedisplay 61 to observe whether the molded piece G is acceptable or not(Steps S5 and S6).

FIG. 1 illustrates a display example of the waveform display section 61v. Change waveforms of Ca, Cb, and Cc shown by the solid lines in FIG. 1are a waveform similar to the change waveforms shown in FIG. 2. Any ofthe change waveforms Ca, Cb, and Cc shows the specific mold status Ac.Change waveforms Cpa, Cpb, and Cpc shown by the virtual line in FIG. 1show a status in which the displacement in the open direction is causedwithout causing the deflection of the movable mold 2 m. Specifically,the status shown in FIG. 6 is caused. In this case, a gap is caused bythe parting opening amount Lm. Specifically, the specific mold status Acis not obtained. So, the specific mold status Ac can be caused byincreasing the mold clamping force and the injection pressure forexample. In FIG. 1, the reference numeral V and P represent the typicalchange waveforms of the injection speed and the injection pressure,respectively.

The injection pressure is optimized by providing the molding injectionpressure Pi under conditions in which the movable mold 2 m and the fixedmold 2 c have therebetween the above-described predetermined parting gapC during the injection filling and a non-defective product can bemolded. Specifically, the injection pressure is appropriately changed soas to always prevent the mold 2 from being abnormally filled with theresin R. By selecting the molding injection pressure Pi having such aminimum value or a value close to the minimum value, the molding moldclamping force Pc also can be set to the minimum value or a value closeto the minimum value. This can consequently provide the optimalperformance from the viewpoint of energy saving and can provide theprotection and a longer service life to a mechanism component forexample. The calculated molding injection pressure Pi is set as alimiter pressure Ps to the injection pressure during the production(Step S7). As described above, by setting the molding injection pressurePi as the limit pressure Ps for the production, then an advantage isobtained in which the molding injection pressure Pi can be alwaysmaintained without controlling the pressure. By repeating these testmoldings with different conditions, the mold clamping force satisfyingthe above-described conditions can be selected. The selected moldclamping force is set as the molding mold clamping force Pc used toperform the mold clamping operation by the mold 2 during the production(Step S8).

In this case, the magnitudes of the mold clamping force and theinjection pressure may be arbitrarily set by an operator or may beautomatically or semi-automatically calculated by additionally using anauto-tuning function provided in the injection molding machine M forexample. When the auto tuning function is used, the mold clamping forceimmediately before the occurrence of burr can be calculated easily.

A speed limit value may be set with regard to the injection speed of theinjection apparatus Mi (Step S9). This speed limit value is not alwaysrequired to be set. However, by setting the speed limit value, the mold2 or an injection screw for example can be mechanically protected if byany chance the injection speed V is excessively high. Thus, the speedlimit value is set to such a value that can provide the mechanicalprotection to the mold 2 and the injection screw for example.

Then, the processing is to set zero reset conditions regarding thedistance measurement sensor 13 for setting the parting gap C (Step S10).In the injection molding machine M according to this embodiment, duringthe production described later, when a predetermined injectionpreparation after at least the mold clamping by the mold clampingapparatus Mc is completed and a predetermined timing is reached, thetiming at which this reset control is performed is set as a reset timingas zero reset conditions in order to perform a reset control forresetting the distance measurement sensor 13 to zero. Other requiredsettings are also performed (Step S11).

Next, the following section will describe the specific processingprocedure using the molding method according to this embodiment withreference to the respective drawings and based on the flowcharts shownin FIG. 12 and FIG. 13.

FIG. 12 and FIG. 13 illustrate the processing procedure during theproduction using the molding injection pressure Pi and molding moldclamping force Pc. FIG. 12 shows the pre-filling step Sa from theinjection preparation to the injection start. FIG. 13 shows the fillingmolding step Sb from the filling start to the molded piece ejection.

First, the switching of the valve circuit 37 and the control of theservo motor 39 are used to drive the measurement motor 25 of theinjection apparatus Mi to subject the resin R to a plasticizationprocessing (Step S21). This molding method does not require ameasurement step as in general molding methods to accurately measure theresin R. Specifically, in the case of the molding method in thisembodiment, the injection step only requires the injection operation tobe carried out until the cavity is filled with the resin R. Thus, theresin R measured to have a slightly-excessive level may be sufficient inthe measurement step. Thus, although the measurement operation isperformed in the general measurement step, a measurement control forobtaining an accurate measurement value is not required.

The switching of the valve circuit 37 and the control of the servo motor39 are used to drive the mold clamping cylinder 27 of the mold clampingapparatus Mc and the mold 2 is clamped so that the molding mold clampingforce Pc set by the mold clamping force is reached (Steps S22 and S23).The status of the clamped mold 2 is the same as the status shown in FIG.5 except for that the resin R is not filled.

When the mold clamping is completed, then the processing related to theinjection preparation is performed (Steps S24 and S25). This processingincludes a nozzle touch by a nozzle touch operation and the control ofthe mold temperature. In the nozzle touch operation, such a control isperformed that the injection apparatus moving cylinder 26 isdrive-controlled to forwardly move the injection apparatus Mi and thenozzle touches the mold 2. The mold temperature is subjected to acontrol processing in which the mold temperature fluctuated due to themold opening reaches a formal set temperature. When these processingsrelated to the injection preparation are completed, the injectionapparatus Mi is put in an injection standby status (Step S26).

At the time point “to” for the injection start, then the switching ofthe valve circuit 37 and the control of the servo motor 39 are used todrive the injection cylinder 24 of the injection apparatus Mi to subjectthe mold 2 to the injection processing of the resin (Steps S27 and S28).In this case, the screw 21 may be moved forward by a rated operation,thus eliminating the need of subjecting the screw 21 to a speed controland a pressure control. The molding machine controller 12 on the otherhand monitors whether or not the set reset timing is reached (Step Sd1).Specifically, when such a setting is performed to set the reset timingto the time point “to” to start the injection (FIG. 2), then theinjection is started when the time point “to” is reached and a resetcontrol is performed to reset the distance measurement sensor 13 to zero(Steps Sd2 and Sd3).

In the manner as described above, the pre-filling step Sa is completed.Next, the processing proceeds to the filling molding step Sb. When theinjection is started at the time point “to”, then the cavity of the mold2 is filled with the plasticized and molten resin R in the heating tube22 (Step S29). With the filled resin R, the injection pressure Pincreases as shown in FIG. 1 and then approaches the limit pressure Psand reaches the limit pressure Ps at which a control for maintaining thelimit pressure Ps, i.e., a control for preventing the overshoot, isperformed to maintain the injection pressure P at the limit pressure Ps(the molding injection pressure Pi) (Steps S30 and S31). Thus, theinjection operation substantially provides a first class pressurecontrol. In FIG. 1, the reference numeral V denotes the injection speedduring this.

The cavity of the mold 2 filled with the resin R allows the mold 2 to bepressurized by the resin R, causing the parting gap C between the fixedmold 2 c and the movable mold 2 m (Step S32). This parting gap C isgenerated based on the molding mold clamping force Pc and the moldinginjection pressure Pi set in advance. Thus, the parting gap C has theinterval of the inner portion Xi larger than the interval of outer edgeportion Xo and the interval of the outer edge portion Xo is equal to orsmaller than the predetermined size Ls including 0. Specifically, theabove-described specific mold status Ac is caused. This can consequentlyprovide a favorable degassing and a non-defective product moldingexcluding defects. During this, the mold 2 is put in the status shown inFIG. 7 or FIG. 8.

When the injection filling of the resin R to the mold 2 is completed,then the resin R is fixated with time passage and this solidificationcauses the natural compression of the resin R (Step S33). Specifically,since the solidification of the resin R causes the reduction of thevolume, the natural compression is performed by the pressurizationaction by the elastic recovery of the mold 2 (the movable mold 2 m inparticular) so as to follow the reduction of the volume. Then, when theset cooling time Tc has passed, the switching of the valve circuit 37and the control of the servo motor 39 are used to drive the moldclamping cylinder 27 to rearwardly move the movable mold 2 m to therebyperform the mold opening. The switching of the valve circuit 37 and thecontrol of the servo motor 39 are used to drive the ejector cylinder 31to protrude the molded piece G attached to the movable mold 2 m (StepsS34 and S35). Then, the molded piece G is removed and one molding cycleis completed.

Thereafter, when the next molding is performed, then the resin R issimilarly plasticized to perform the injection preparation and thenprocessings such as a mold clamping, injection, or cooling may besimilarly performed (Steps Sr, S21, and S22 . . . ).

On the other hand, at least in a period from the time point “to” of theinjection start to the completion of the cooling of the mold 2, thechange data of the parting gap C is detected. Specifically, the distancemeasurement sensor 13 is used to detect the magnitude of the parting gapC to time (change data) with a fixed sampling time interval. As aresult, the detected change data of the parting gap C is given to thecontroller body 63. The waveform is displayed as needed on the waveformdisplay section 61 v shown in FIG. 1 in the display 61 in accordancewith the progress of the molding step. In this case, the time along thetime axis of the horizontal axis is secured at least from the time point“to” at the injection start to the completion of the cooling of the mold2. As a result, the operator can use the waveform display section 61 vto monitor the waveform change of the parting gap C of the mold 2showing the operation waveform at the mold clamping apparatus Mc side.

As described above, the molding machine controller 12 is configured sothat the change data corresponding to a period from the injection startdetected by the distance measurement sensor 3 to the completion of thecooling of the mold 2 is displayed by the waveform display section 61 vof the display 61 attached to the molding machine controller 12. Thisconfiguration can provide the visual monitoring of the change of theparting gap C of the mold 2 showing the operation waveform at the moldclamping apparatus Mc side in an easy and effective manner. In addition,by the above-described zero reset effect, accurate waveforms for whichthe respective parting gaps C . . . have the same zero point can bedisplayed (and displayed in a superposed manner).

As a result, during an injection standby operation from the moldclamping operation to the injection start operation, the set moldingmold clamping force Pc is maintained. Even when disturbance factors arecaused by the fluctuation of the mold temperatures at the respectiveshoots and the operations in other parallelly performed steps, anunnecessary influence on the status of the parting gap C can beexcluded, thus stably collecting accurate data related to the partinggap C. As a result, the respective parting gaps C . . . having the samezero point can be appropriately monitored and molded pieces G can besubjected to a processing to determine whether or not the molded piecesG are acceptable, thus also contributing to the improvement of the yieldrate.

As shown in FIG. 13, the change data of the parting gap C may bemonitored by setting a monitoring width as a set range to determinewhether or not the change data is acceptable Steps Sm1 and Sm2). Thisconsequently always provides an appropriate determination for theacceptability. When the data deviates from the set range (monitoringwidth) in the processing for the determination for the acceptability, arequired error processing can be performed (Step Sm3).

Thus, the molding method (the injection molding machine M) according tothis embodiment includes, in a basic configuration function, the moldclamping apparatus Mc that provides, by the solidification of the resinR in the mold 2, at least the natural compression of the resin R due tothe elastic recovery of the mold 2. The specific mold status Ac iscaused in which, during the injection filling, the interval of the innerportion Xi in the parting plane direction of the parting gap C betweenthe fixed mold 2 c and the movable mold 2 m is larger than the intervalof the outer edge portion Xo and the interval of the outer edge portionXo is equal to or lower than the predetermined size Ls including 0. Themethod includes the control means 3 having the setting function Fs forsetting the molding injection pressure Pi that is an injection pressureat which a non-defective product can be molded and the molding moldclamping force Pc that is a mold clamping force by which a non-defectiveproduct can be molded, and the control function Fc for using, during theproduction, the molding mold clamping force Pc to clamp the mold 2 andfor injecting and filling the resin R into the clamped mold 2 by themolding injection pressure Pi and for performing a control removing themolded piece G after the passage of the predetermined cooling time Tc.Thus, the parting gap C can have the outer edge portion Xo side and theinner portion Xi side having different intervals (magnitudes).Specifically, the inner portion Xi side can have the parting gap Chaving an interval providing the optimal natural compression to theresin R. The outer edge portion Xo side can have the parting gap Chaving an optimal interval from the viewpoints of the degassing from themold cavity and burr prevention for example, thus optimizing theinterval and shape of the parting gap C for example. This canconsequently secure the effect of the conventional molding method forsetting the interval of the parting gap C only, i.e., molded pieces Ghaving the highest quality and homogeneity and also can further improvethe effects including the ones to achieve simpler molding conditions andeasier setting, easier quality control, and a shorter molding cycle timefor example.

Preferred embodiments have been described in detail in the abovesection. However, the invention is not limited to the above embodiment.The detailed configuration, shape, number, or method for example can bearbitrarily changed, added, or omitted within a range not deviating fromthe summary of this invention.

For example, the non-contact distance measurement sensor 13 wasillustrated as the gap status detector 11 for detecting the status ofthe parting gap C. However, various sensors that can accurately detectthe parting gap C can be used including various non-contact distancemeasurement sensors such as a proximity sensor or an angle sensor fordirectly detecting the change angle Qm. The interval of the outer edgeportion Xo in the parting gap C is desirably set to 0.3 [mm] or less butalso may be set to a value exceeding 0.3 [mm] depending on the type ofmolding material to be used or molding conditions for example. A casehas been illustrated in which a direct pressure-type hydraulic moldclamping apparatus was used as the injection molding machine M. However,a toggle-type electric mold clamping apparatus also may be used. In thiscase, it is more desirable that a toggle link mechanism can be put in anon-lockup status.

INDUSTRIAL APPLICABILITY

The molding method according to this invention can be used for variousinjection molding machines in which a mold clamped by a predeterminedmold clamping force is filled with injected resin by a predeterminedinjection pressure to perform a molding operation.

REFERENCE SIGNS LIST

2: Mold, 2 c: Fixed mold, 2 m: Movable mold, 3: Control means, M:Injection molding machine, Mi: Injection apparatus, Mc: Mold clampingapparatus, R: Resin, C: Parting gap, Xi: Inner portion of parting gap(parting plane direction), Xo: Outer edge portion of parting gap(parting plane direction), Ac: Specific mold status, (Pi): Moldinginjection pressure, (Pc): Molding mold clamping force, Fs: Settingfunction, Fc: Control function, G: Molded piece

CITATION LIST Patent Literature 1

International Publication WO2011/161899

1. An injection molding machine comprising a mold clamping apparatus forclamping a mold consisting of a fixed mold and a movable mold by apredetermined mold clamping force and an injection apparatus forallowing the clamped mold to be filled with injected resin by apredetermined injection pressure, characterized in comprising: a moldclamping apparatus for providing at least the natural compression of theresin due to the elastic recovery of the mold in accordance with thesolidification of the resin in the mold, a specific mold status iscaused during the injection filling in which the interval of the innerportion in a parting plane direction of a parting gap between the fixedmold and the movable mold is larger than the interval of an outer edgeportion and the interval of the outer edge portion is equal to orsmaller than a predetermined size including 0, and a control meanshaving a setting function for setting a molding injection pressure thatis an injection pressure at which a non-defective product can be moldedand a molding mold clamping force that is a mold clamping force by whicha non-defective product can be molded, and a control function for using,during the production, the molding mold clamping force to clamp the moldand for injecting and filling the resin into the clamped mold by themolding injection pressure and for performing a control removing themolded piece after the passage of the predetermined cooling time.
 2. Theinjection molding machine according to claim 1, wherein: the controlmeans includes a molding machine controller that detects, during theinjection filling, a relative change angle between the respective outerfaces of the fixed mold and the movable mold abutted to the outer edgeportion to perform, based on this change angle, a control formaintaining the specific mold status.
 3. The injection molding machineaccording to claim 2, wherein: the control means includes a gap statusdetector for detecting, during the injection filling, a physical amountcorresponding to the relative change angle between the respective outerfaces of the fixed mold and the movable mold abutted to the outer edgeportion and a molding machine controller for performing, based on thephysical amount corresponding to the change angle obtained from this gapstatus detector, a control for maintaining the specific mold status. 4.The injection molding machine according to claim 3, wherein: the gapstatus detector is provided between the outer face of the fixed mold andthe outer face of the movable mold and has a non-contact distancemeasurement sensor consisting of a projection section provided at one ofthe fixed mold and the movable mold and a reflecting section provided atthe other, and this distance measurement sensor is used to detect ameasurement distance showing a physical amount corresponding to thechange angle.
 5. The injection molding machine according to claim 4,wherein: the projection section and the reflecting section provided inthe distance measurement sensor are provided at a position away from theouter face in the outer direction in the orthogonal direction by a fixeddistance or more.
 6. The injection molding machine according to claim 4,wherein: the projection section and the reflecting section are supportedby a support stay having a predetermined length provided at the outerface in a protruding manner, respectively.
 7. The injection moldingmachine according to claim 6, wherein: the projection section and thereflecting section include a support mechanism supported by the supportstay, respectively, and this support mechanism is used to adjust atleast a distance from the outer face to the projection section and thereflecting section.
 8. The injection molding machine according to claim4, wherein: the projection section and the reflecting section providedin the distance measurement sensor have a predetermined interval duringthe mold clamping prior to the injection filling and are arranged so asto be able to detect at least a change distance in a shorteningdirection.
 9. The injection molding machine according to claim 1,wherein: the setting function of the control means has a function to setthe molding injection pressure as a limit pressure during theproduction.
 10. The injection molding machine according to claim 1,wherein: the mold clamping apparatus uses a direct pressure-typehydraulic mold clamping apparatus.
 11. The injection molding machineaccording to claim 1, wherein: the mold clamping apparatus uses atoggle-type electric mold clamping apparatus.
 12. A molding method of aninjection molding machine, wherein: a mold consisting of a fixed moldand a movable mold clamped by a mold clamping apparatus with apredetermined mold clamping force is filled with injected resin by aninjection apparatus with a predetermined injection pressure to perform amolding operation, a mold clamping apparatus is used to provide at leastthe natural compression of the resin due to the elastic recovery of themold in accordance with the solidification of the resin in the mold, aspecific mold status is caused in advance during the injection fillingin which the interval of the inner portion in a parting plane directionof a parting gap between the fixed mold and the movable mold is largerthan the interval of an outer edge portion and the interval of the outeredge portion is equal to or smaller than a predetermined size including0, a molding injection pressure is set that is an injection pressure atwhich a non-defective product can be molded and a molding mold clampingforce is set that is a mold clamping force by which a non-defectiveproduct can be molded and, during the production, the molding moldclamping force is used to clamp the mold and the resin is injected andfilled into the clamped mold by the molding injection pressure and themolded piece is removed after the passage of the predetermined coolingtime.
 13. The molding method of the injection molding machine accordingto claim 12, wherein: the interval of the outer edge portion in theparting gap is set to 0.3 [mm] or less.
 14. The molding method of theinjection molding machine according to claim 12, wherein: during theinjection filling, the relative change angle between the respectiveouter faces of the fixed mold and the movable mold abutted to the outeredge portion is detected and, based on this change angle, a control isperformed to maintain the specific mold status.
 15. The molding methodof the injection molding machine according to claim 14, wherein: duringthe injection filling, a physical amount corresponding to the relativechange angle between the respective outer faces of the fixed mold andthe movable mold abutted to the outer edge portion is detected and,based on the physical amount corresponding to the change angle, acontrol is performed to maintain the specific mold status.
 16. Themolding method of the injection molding machine according to claim 15,wherein: a physical amount corresponding to the change angle is detectedin a mechanically-amplified manner.
 17. The molding method of theinjection molding machine according to claim 12, wherein: the moldinginjection pressure is set as a limit pressure during the production. 18.The injection molding machine according to claim 5, wherein: theprojection section and the reflecting section are supported by a supportstay having a predetermined length provided at the outer face in aprotruding manner, respectively.
 19. The injection molding machineaccording to claim 5, wherein: the projection section and the reflectingsection provided in the distance measurement sensor have a predeterminedinterval during the mold clamping prior to the injection filling and arearranged so as to be able to detect at least a change distance in ashortening direction.